fix(toc): update max-height calculation for TOC content to use variable

assets/css/_core/_widgets/_fixed-button.scss

@@ -18,15 +18,13 @@
   background-color: light-dark(#f1f1f1, #1e1e1f);
 
   &:hover,
-  &:active {
+  &:active,
+  &:focus {
+    outline: none;
     color: fixit-var(global-font-color);
     cursor: pointer;
   }
 
-  &:focus-visible {
-    outline: -webkit-focus-ring-color auto 1px;
-  }
-
   @include media('print') {
     display: none !important;
   }

assets/css/_page/_single/_toc.scss

@@ -122,8 +122,7 @@
   .toc-content {
     overflow-y: auto;
     overscroll-behavior: contain;
-    // TODO 这里计算错误，待重构使用 JS 计算
-    max-height: calc(100vh - #{2 * #{fixit-var(header-height)}});
+    max-height: fixit-var(toc-content-max-height, calc(100dvh - #{2 * #{fixit-var(header-height)}}));
     @include scrollbar-width(none, 0);
 
     &.always-active ul,